Organic foods can be labelled "GM-free" even if they contain up to 0.9% genetically modified content, European agriculture ministers decided yesterday.

The decision provoked outcry among environmental campaigners and supporters of organic farming, who said it would lead to "genetic contamination".

The ministers' meeting in Luxembourg supported commission arguments that setting a lower limit of 0.1% , the lowest level at which GM organisms could be scientifically detected, would place standards which would make organic produce too expensive for farmers.

The higher ceiling was sufficient for "accidental or technically unavoidable" presence of approved GMOs. The agriculture commissioner Mariann Fischer Boel said: "It can be very tempting to say 'zero tolerance'. but that wouldn't work in real life. To avoid accidental contamination, it would be so expensive to produce organic products that it would damage the market completely; it would simply kill the sector." The labelling agreement would, she said, give consumers "assurances of precisely what they are buying".

Helen Holder, of Friends of the Earth Europe, warned that traces of GM in organic food would quickly become "acceptable" to the authorities, and "organic farmers will find it increasingly difficult to keep their crops GM-free".

Marco Contieri, of Greenpeace, said: "The lax attitude taken by the European commission and some member states disregards the preferences of European consumers and may put the whole organic sector at risk."

He said: "In practice, low levels of GM material could start slipping into all organic food."

Some agriculture ministers too are uneasy. Josef Proell, of Austria, said: "It is clear this [threshold] is not a licence to contaminate. Any contamination would have to be involuntary and unavoidable. We cannot simply go on raising the threshold and pretend we are on a path to organic farming."

There are already concerns about arrangements if GM crops are cleared to be grown commercially in Britain over the next few years. The government has made clear it believes consumers will have to put up with some cross-contamination. But groups like the Soil Association in the UK argue that GM technology is "past its sell-by date" and consumers have rejected the idea of GM food.

Yesterday's decision brings the European rules for "GM-free" labelling on organic food into line with that which exists for non-organic food. But the Soil Association and other certification bodies do not allow any organic content.